Materials and Methods:
This is a single-center, retrospective cohort study that was approved by
the Institutional Review Board at Ochsner Medical Center, New Orleans,
LA. This retrospective study involving human participants was in
accordance with the 1964 Helsinki Declaration and its later amendments
or comparable ethical standards.
Echocardiograms saved in the institutional database (Cardiovascular
Imaging System, New Orleans, LA) between 2007 and 2016 were screened
with the keywords of MS, MAC, rheumatic, or diastolic doming of the
anterior mitral valve leaflet. We obtained demographic and clinical data
from electronic medical records (EPIC, Verona, WI, USA), including age,
body mass index, gender, history of diabetes, hypertension, chronic
kidney disease (eGFR < 60 mL/min per 1.73
m2), ESRD on dialysis, prior radiation exposure,
coronary artery disease defined by either history of acute coronary
syndrome or abnormal ischemic evaluation, and history of chronic heart
failure. Survival and mortality data were obtained retrospectively from
electronic medical records in July 2020.
Based on echocardiographic findings, DMS was defined in our study with
the presence of severe MAC that extends onto the leaflets causing
restricted leaflet mobility and LV inflow obstruction. Eligible studies
had at least mild MS reported by transthoracic echocardiogram with a
mean TMPG of ≥ 4 mmHg. Patients with prior mitral balloon valvuloplasty,
ejection fraction < 50%, heart rate ≥ 100 bpm, severe aortic
stenosis, and more than mild MR or mild aortic regurgitation were
excluded. Patients with RMS who met inclusion and exclusion criteria
were used as the comparison group. A total of 64 patients with DMS and
24 patients with RMS met the initial inclusion criteria. We excluded
patients with ESRD (6 in DMS and 1 in RMS group) for analyses related to
valve area and pressure gradient because of possibly increased gradients
due to high flow state and volume overload.
Echocardiography studies were performed according to the American
Society of Echocardiography guidelines using either GE Vivid E9 and E95
ultrasound system (GE Vingmed, Horten, Norway) and reviewed and verified
by a Level III-trained echocardiographer.17–19 MAC
severity in the DMS cohort was scored as reported in Movva et
al.6 The MVA by continuity equation
(MVACEQ) was used as the independent reference and
calculated with the following equation: MVACEQ(cm2) = (LVOT diameter)2 x 0.785 x
(VTILVOT / VTIMV).11.
Continuous-wave Doppler imaging of the MV from the apical four-chamber
view was used to obtain the peak and mean TMPG, as well as the
velocity-time integral (VTI) of the MV. Peak E (early diastolic
velocity), peak A (late diastolic velocity), and deceleration time were
measured with pulse wave Doppler of the MV inflow at the MV tips in the
apical four-chamber view during diastole. The LV outflow tract (LVOT)
diameter was measured in the parasternal long-axis view (inner edge of
the septal endocardium to the inner edge of the anterior mitral leaflet
in mid-systole). The LVOT VTI was measured by tracing the instantaneous
dense modal velocities throughout the systole of the LVOT pulse wave
Doppler sample taken 1 cm below the aortic valve in the apical long-axis
view. LVOT stroke volume (SV) was calculated with the following
equation: SVLVOT (cm3) = 0.785 x
DiameterLVOT2 x
VTILVOT. The DMSI was calculated as follows: DMSI =
VTILVOT / VTIMV (Figure 2 ).
Three cardiac cycles were averaged for Doppler-related calculations for
patients in sinus rhythm and five cardiac cycles for patients in atrial
fibrillation (AF). A level III trained echocardiographer repeated all of
the measurements for the study purposes. Two separate level-III trained
echocardiographers performed the interclass correlation analysis.